Purpose: Our study aimed to investigate the relationship between MALAT-1 (metastasis-associated lung adenocarcinoma transcript 1) expression and the chemotherapy drug resistance in osteosarcoma.
Methods: The U-2OS osteosarcoma cell line was selected for the experiment. The cells were treated with methotrexate, doxorubicin, cisplatin, and ifosfamide, respectively. RT-PCR was applied to detect the MALAT-1 expression in cells. The doxorubicin-resistant cell line was constructed. The cells were divided into doxorubicin-sensitivity group (DS/shCtrl), doxorubicin-resistance group (DR/shCtrl) and shMALAT1-doxorubicin-resistance group (DR/shMALAT1). The colony formation assay and 5-ethynyl-2ʹ-deoxyuridine (EdU) assay were used to detect cell proliferation. PI staining was used to detect the cell cycle. Transwell assay and wound healing assay were used to observe the migration and invasion ability. Annexin V-FITC assay was used to detect cell apoptosis. Western blot was used to detect the protein expression and potential mechanism. The impacts of MALAT-1 expression were verified in vivo.
Results: The MALAT-1 was upregulated in the doxorubicin-resistant U-2OS osteosarcoma cells. Downregulating MALAT-1 in the doxorubicin-resistant cells inhibited the proliferation, migration, and invasiveness, increased the ratio of cells in the G0/G1 phase, promoted apoptosis. In the doxorubicin-resistant U-2OS cells, the extracellular regulated protein kinases (ERK) phosphorylation was declined, which could be reversed by downregulating MALAT-1. In vivo assay indicated that the growth of doxorubicin-resistant solid osteosarcoma could be suppressed by downregulating MALAT-1.
Conclusion: Our study provides evidence that doxorubicin may upregulate MALAT-1 in osteosarcoma. Downregulating MALAT-1 in the doxorubicin resistance U-2OS cells could reverse the resistance and may improve chemotherapeutic efficiency. Some conclusions in previous literature may be one-sided.

Keywords: osteosarcoma, doxorubicin, long noncoding RNA, MALAT-1, chemotherapy resistance, extracellular regulated protein kinases


中文翻译：

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MALAT-1 与 U-2OS 骨肉瘤细胞中的多柔比星耐药性有关

目的：我们的研究旨在探讨 MALAT-1（转移相关肺腺癌转录本 1）表达与骨肉瘤化疗耐药之间的关系。
方法：选择U-2OS骨肉瘤细胞系进行实验。分别用甲氨蝶呤、多柔比星、顺铂和异环磷酰胺处理细胞。应用 RT-PCR 检测细胞中 MALAT-1 的表达。构建了多柔比星抗性细胞系。将细胞分为多柔比星敏感性组（DS/shCtrl）、多柔比星抗性组（DR/shCtrl）和shMALAT1-多柔比星抗性组（DR/shMALAT1）。集落形成测定和5-乙炔基-2′-脱氧尿苷（EdU）测定用于检测细胞增殖。PI染色用于检测细胞周期。Transwell试验和伤口愈合试验用于观察迁移和侵袭能力。膜联蛋白V-FITC测定用于检测细胞凋亡。Western blot检测蛋白表达及潜在机制。
结果： MALAT-1 在多柔比星耐药的 U-2OS 骨肉瘤细胞中上调。下调多柔比星耐药细胞中的MALAT-1抑制增殖、迁移和侵袭，增加G0/G1期细胞比例，促进细胞凋亡。在多柔比星耐药的 U-2OS 细胞中，细胞外调节蛋白激酶 (ERK) 磷酸化下降，这可以通过下调 MALAT-1 来逆转。体内试验表明，通过下调 MALAT-1 可以抑制多柔比星耐药实体骨肉瘤的生长。
结论：我们的研究提供了多柔比星可能上调骨肉瘤中的 MALAT-1 的证据。下调多柔比星耐药 U-2OS 细胞中的 MALAT-1 可以逆转耐药性并可能提高化疗效率。以往文献中的一些结论可能是片面的。

关键词：骨肉瘤，阿霉素，长链非编码RNA，MALAT-1，化疗耐药，细胞外调节蛋白激酶